Vehicles such as lawn and garden tractors with PTO driven attachments, or mowing vehicles, may include an interlock circuit with several functions including the prevention of PTO operation when the tractor or vehicle travels in reverse. Under certain conditions, operation of the PTO or mowing blade(s) while the tractor or vehicle travels in reverse is necessary or desired. This may be referred to as a reverse implement option. Various override or bypass systems have been proposed for this purpose. Some of the override or bypass systems may also be referred to as latch circuits, which typically require the operator or driver to actuate one or more switches. For example, U.S. Pat. No. 5,994,857 assigned to Deere and Company of Moline, Ill., relates to an interlock circuit having several relays and a hand operated PTO switch provided with a momentary on (or override) position to allow operation of the PTO while the tractor or vehicle travels in reverse. U.S. Pat. No. 6,316,891, also assigned to Deere and Company, describes an interlock circuit having only a single relay, and an override or bypass system that does not require the operator to continuously push or hold the hand operated PTO switch to permit PTO operation while traveling in reverse.
Override or bypass systems may include a reverse sensing switch, in addition to a hand operated PTO switch. For example, the override or bypass system may allow PTO operation if a hand operated PTO switch is moved to a momentary on (or override) position, and the reverse sensing switch is closed or actuated, indicating the vehicle is in reverse. In vehicles having hydrostatic transmissions, the reverse sensing switch may be on the transmission or hydrostatic control rod.
After the operator actuates a hand operated PTO switch, the PTO override system may allow PTO operation to begin when the operator depresses the reverse foot pedal sufficiently for the reverse sensing switch to detect the tractor or vehicle is in reverse. The reverse sensing switch may detect the tractor or vehicle is in reverse beginning at a speed of zero mph. However, when the operator steps on the reverse pedal, the reverse sensing switch may not detect the tractor or vehicle is in reverse until after it has begun traveling in reverse. The reverse sensing switch may not be actuated at the same speed for all tractors or vehicles and/or operating conditions. For example, some machines or operating conditions may not detect the vehicle is in reverse and allow PTO operation until it reaches a speed of 0.75 mph in reverse. The override or bypass system also may unlatch at different speeds, depending on the tractor or vehicle condition and the operating conditions.
There is a need for a reverse implement option for a lawn and garden tractor or mowing vehicle that will provide a more predictable start of PTO operation when the tractor or vehicle begins travel in reverse. There is a need for more consistent PTO operation for traveling in reverse across different tractors or vehicles, and for different operating conditions.